Controlled humidity refrigerator



Filed Nov. 28, 1944 2 Sheets-Sheet 1 Mayzs, 194s. J J, BAUMAN 2,442,188

CONTROLLED HUMIDITY REFRIGERATOR Filed Nov. 28, 1944 2 Sheets-Sheet 2 1 S 23 muuu r IIIH@ l .nmunum u 3.33 Jijy Ilill Yad/x Patented May 25, 1948 'um-'reo STATES v'Pirrairr ori-ica 2,442,188 CONTROLLED HUMIDITY REFRIGEBATOR John -J. Bauman,

Abington, Pa., assignor, by

menne assignments, to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application Nember 2s, 1944, semi No. 565,435

(ci. (sz-1oz) l 18 Claims.

1 This invention relates to refrigeration apparatus, and is particularly concerned with refrigerators which include a high humidity comair in one compartment is maintained above that existing in other portions of the-box, and the relative humidity in said compartment is kept at a high value.

In refrigerators incorporating high humidity compartments, it has proven difiloult to insure the desired degree oi humidity throughoutallseasons ofthe year, while still preventing the humidity from reaching undesirably high values at certain times, andvparticularly in damper climates.

As set forth in the copen'ding application of Malcolm G. Shoemaker, Ser. No. 528,581, ilied March 29, 1944, now Patent No. 2,416,354, granted February 25, 1947, and assigned to the assignee of the instant invention, excessively high humidity results in undesirable condensation of moisture upon the walls and other surfaces exposed within the so-called moist-cold space. The reason for this will be apparent when it is understood that such walls andvsurfaces are apt to assume temperature values well below the dew-point temperature of the compartment air, at the undesirably high relative humidity conditions frequently encountered in` said compartments.

In the structure'llustrated in the above-mentioned copending application, humidity-responsive means is provided which removes undesired moisture from the compartment air, as and when required, by passing said air in heat exchange relation with an evaporator maintained at relatively low temperature, which evaporator is also utilized for the production of ice cubes as well as for low-temperature storage purposes. the construction of the above-mentioned application is highly advantageous, in that it provides the desired control of the moisture content of the compartment air, it inherently places certain restrictions on the flexibility and adaptability of the design, as will now be apparent.

In refrigerators having provision for air circulation past a relatively low temperature element, the moisture condensed in that zone or passage which is in heat exchange relation with said cold element must be prevented from accumulating in the form of frost, as accumulation of frost therein restricts the passage area. and reduces the necessary heat exchange.

Hence, if the zone or passage utilized to eil'ect the moisture removal is normally operated below 32 F., it must lbe brought above the freezing temperature during at least a portion of the refrigerating cycle, but, on the other hand, it will be evident that the condensation of moisture will be facilitated-by the maintenance of a relatively low temperature in said zone. Therefore, it would be highly desirable to maintain the moisture condensing zone at temperatures well below freezing, so long as it is possible to periodically raise the temperature of said zone for intervals of sufficient duration'to insure melting of any frost which has accumulated. While prov ision has been made to prevent the accumulation of such frost in the prior type of apparatus,

the inherent uniformity and the relatively low value of the temperature maintained in the evaporator past which the air is circulated, makes it difficult to operate said zone, in the system of said copending application, at as low a temperature as would otherwise be desired, while still insuring that the zone will periodically pass above the freezing point. This dimculty results While Vfrom the fact that the temperature of the evaporator with which the zone is associated cannot normally be permitted to fluctuate substantially, because of the other requirements and functions of said evaporator, mentioned above. Therefore, means must be provided to keep the zone itself at or near 32 F., to insure that it will pass above the freezing point, during at least a part of the refrigerating cycle of said associated evaporator. This relatively high zone temperature. in turn, requires that said zone be of substantial area, in order to provide heat exchange of magnitude sufficient to accomplish the desired condensation.

By the present invention, these diillculties and design disadvantages previously encountered are eliminated and, to this end, it is a primary object of this invention to provide a refrigerator having a condensing zone which will not only operate at temperatures well below 32 F., but will also automatically attain a temperature, periodically, which is high enough to completely, eliminate the possibility of frost accumulation in said zone.

- provision for the removal of the condensed moisture, while still preventing ingress of additional moisture-laden air into the refrigerator, through the removal passages.

The foregoing and other objects and advantages of the invention may be clearly understood by reference to the following description, taken in conjunction with the accompanying drawings, in which:

Fig. 1 is an elevational view of a refrigerator embodying the invention, portions thereof being broken away to facilitate illustration;

Fig. 2 is a sectional view taken through` the longitudinal vertical mid-plane of the condensing zone or passage, included in the apparatus illustrated in Fig. 1;

Fig. 3 is an enlarged view in perspective of the rear of the refrigerator inner liner and associated' structures, fragmentary portions being broken away; and,

Fig. 4 is a fragmentary illustration of a detail of the construction.

Making particular reference to Figs. 1 and 3 of thedrawlngs, there is illustrated a domestic refrigerator of the mechanical type which includes an outer shell 2, which may be of any well-known type and construction, and an inner metal shell or liner member 3 providing the main food storage space, indicated generally at 4. This space 4 is fitted with a plurality of shelves 5, of any desiredtype. Vertical and horizontal breaker strips 6 and 1, respectively, of low thermal conductivity, are itted around the forward marginal edge of the cabinet opening, while thermal insulation, portions of which are indicated at 8, completely surrounds the inner liner member 3 as well as the outside surfaces of the cooling means presently to be described. The cabinet would, of course, be provided with a door (not shown) said door being adapted to seat thereagainst in the plane of the breaker strips and 1.`

A machinery compartment 9 is located in the lower portion of the cabinet structure, this compartment housing the motor-compressor unit indicated generally at I0. The main food storage and ice freezing evaporator is shown at II and includes, generally, a relatively large well-type frozen food storage area I2. to which access may be had through an opening I3, and a smaller ice freezing space indicatedat I4. A storage area I 5 is located to the right of the ice freezing section as viewed in Fig. 1 and is particularly adapted for the preservation of meats, and the like. This evaporator may be supported within the refrigerator in any convenient manner, as for example, by'securing its outer, vertical walls to an inturned flange I6 formed about the lower edges of the inner liner 3. Certain features of the particular evaporator illustrated are disclosed and claimed in the copending application of Donald E. Dailey, Serial No. 515,950, led December 28, 1943, now Reissue Fatent No. 22,976, granted February 24, 1948, and as such features, per se, form no part of the present invention, detailed description of such features is not deemed necessary herein.

In the embodiment illustrated, and as clearly appears in Fig. 1, a double-thickness insulating partition I1 provides the floor for the main storage compartment 4, this partition being interposed between the sections of the main evaporator and said food storage compartment, in order to make it possible to operate the compartment .4 at relatively high temperatures as compared and freezing sections I2, I4 and I5, and to prevent the undesired frosting-out of moisture present in said compartment 4. As clearly appears in the drawing, a gasket member I8 surrounds the partition I1, said gasket being interposed between the partition members and the adjacent wall portion of the inner liner 3.

'I'he main food storage section 4 is cooled by means of refrigerant tubing I9 secured in convoluted arrangement about the exterior surface of the inner liner, and constituting the evaporator portion of a secondary refrigerant circuit of known type. Condensation of the secondary liquid is effected by means of heat exchange association between a condensing portion 29 of the secondary tubing and a small evaporator 2| (see Fig. 3) which constitutes a series-connected portion of the main primary circuit utilized-to effect refrigeration of the evaporator sections I2 and I4. As best appears in Fig. 3, the condensing tubing 20 and thesmall primary evaporator 2| are each carried by a metallic plate 22 and 23,'

respectively, said plates being arranged in high heat conducting relation and secured to the rear portion of the inner liner by any convenient means, as for example, by the brackets illustrated at 24. While the refrigerant flow circuits will be pointed out more fully just below, a detailed description of the relationship and functioning of the primary-secondary circuits is not necessary herein, since the invention is not concerned therewith.

For a purposeV which willv appear hereinafter, the operation of the motor-compressor I0 kis controlled in response to the temperature of the associated plates 22 and 23 and, for that purpose, a suitable feeler tube 25 (see Fig. 1) is mounted against the face of plate 22. This feeler tube is connected to the expansi-ble bellows 26 of a thermostatic switch 21 of well-known type. Closure of the switch 21 will initiate operation ofthe motor-compressor I0 by connecting it across the line 28, as is evident from the drawing. Although the control switch 21 has -been illustrated conventionally, it will be understood that a control is contemplated which is of the Vusual type providing a temperature diierence of several degrees, between open and closed positions. That is, after opening of the switch contacts, reclosurev through a, capillary tube 3|, a portion of which l is arranged in heat exchange relation with the lower portion of a suction line 32. From the entry tubing 3U the volatile refrigerant passes through refrigerant flow passages` 33 arranged about the evaporator storage section I2, a suitable restrlctor 34 being interposed between the courses of tubing 39 and the convolutions 33, in order to maintain the low temperature desired n for the proper preservation of frozen foodstuffs.

From the tubing 433 surrounding the storage compartment I2, the refrigerant is delivered toV with the temperature ofthe storage,

f Y El A] l frigerant contained in the secondary condensing tubing 20, as above described, the primary refrigerant is returned to the ycompressor unit through the downwardly extending suction con- 'duit 32. It should be observed that the primary .refrigerant leaving the ev orator 2| is ilrst delivered to an upper portio 32a of said suction line, which portion, as clearly appears in Fig. 2, extends downwardly through an airflow passage 36 secured to the rear face of the inner liner member 3. This portion of the construction is of particular importance in connection with the instant invention and will be described in greater detail hereinafter.

It should be borne in mind that, in common with the aforementioned Shoemaker application, the invention is concerned with an arrangement in which undesired humidity in the nrain food storage compartment, is eliminated by effecting periodic circulation of the compartment air through certain ducts associated with said comI partment, and thence into a passage or zone arranged in heat exchange relation with a normally cold element. In such a system, there is a transfer of latent heat from the moisture-laden air to the cold element referred to and, consequently, some of the moisture is condensed upon surfaces of this dehumidifying zone. Following this, the air whose absolute humidity has now been -substantially decreased is re-inje'cted into the food storage compartment and, combining with the air in said compartment, acts to lower the overall relative humidity therein.

In the apparatus of the present invention this circulation is effected, as and when required, by means of a motor 31 and associated blower 38, operable periodically in response to the humidity conditions existing in the compartment l.

This controlled circulation may conveniently be initiated by means of a humidostat 39 which, while it may be of any desired type, i-s illustrated as being of the type disclosed and claimed in my copending application, Ser.` No. 537,701 filed May 27, 1944. Description' of the humidostat is unnecessary herein, beyond mentioning that the humidostat is adapted to initiate operation of the motor 31 when the relative humidity in the compartment 4 has risen just above a predetermined Value. This is accomplished lthrough conductors 39a and 31a which, in

response to operation of the humidostat, serve to connect the motor across the line 28 through the motor-control contacts of the humidostat, as fully set forth in my copending application identified above. Further, it will be evident that while humidostat control is preferable, it would be possible to effect periodic actuation of the air circulation blower .by other means. For example, the motor 31 could be energized at periodic, timed intervals, in accordance with the average humidity conditions encountered in practice in any particular locality. Further, in the broad aspect, certain advantages of the present invention could be realized by a slow, continuous circulation of the compartment air by means of the blower 38.

Referring now with more particularity to the construction and operation of the dehumidifying apparatus of the present invention, it will be seen that the air-flow passages, see for example the passage 36, preferably comprise duct work taking the form of substantially half-round tubing secured to the face of the inner liner 3 by means oi' flanges 43, which may be bonded to the exterior wall of the liner in any convenient manner. A generally c-shaped air withdrawal duct Il extends about the -side and rear walls of the liner 3 in the lower portion thereof and, as

`shown at 42, apertures are provided inthe linerl wall in registry with this duct portion 4I. A similar air injection duct 43 extends about the upper portion of the liner member, the liner wall again being apertured as at Il to permit passage of air from said duct 43 into the food compartment 4.

The duct 3B extends between the upper and lower air passages M and I3 and, as designated by arrows appearing in the drawings, it will be apparent that thel air is withdrawn from the compartment through duct 4I, passes upwardly (see Figs. 3 and 4) into the-inflow portion of the blower unit 33 and thence upwardly through passage 36 in heat exchange relation with portion 32a of the suction line, the circuit being completed by re-injection of air into. the box through apertures Il communicating with the upper passage I3.

The portion 32a of the suction line is provided with spiral ns 'l5 to increase the active heat exchange. surface, and it is here that the aforementioned transfer of latent heat occurs, and the condensation of excess moisture takes place. It will be noted that the duct 36 carries opposed baffles I6 providing a circuitous path for the air,

and thereby further insuring sufcient heat exchange between said air and the suction line 32a, whereby'to effect the desired moisture-condensation.

vAs is known in the refrigeration art, the re-v frigerant leaving an evaporator may, if desired, be in an active state, at least to some extent, and as a consequence, heat is taken up through the -suction line which becomes, in effect'I an extension of the evaporator. This action occurs when active refrigerant is being pumped through the system by the motor-compressor, and diminishes or disappears, while said motor-compressor is idle. As a result, during the "on" cycle of the motor-compressor, a sub-freezing zone commonly extends back the suction line toward the motor-compressor. The termination of this sub-freezing zone is known as the frost" line and, as indicated above, the excursion of this frost line varies as between on and off portions of the motor-compressor cycle. The degree of such excursion can be very readily controlled by the amount of refrigerant charge in the system, and tests have established that such frost line excursion may be very closely held within predetermined limits.

While, in the apparatus of the present invention, the amount of 'refrigerant charge would necessarily vary with the specific design desired, the invention contemplates charging the system to a degree just sufcient to insure that frost line excursion will occur as follows, The system is so charged that, during on portions of the motor-compressor cycle, the frost line will extend down the suction line to a point just short of I the region where said suction line extends out of duct 36. Thus, it will be evident that, duringv each off period of the compressor l0, the sucsurfaces is comparatively small and that.l asfaconsequence, said line and surfaces will require a very short time tolpass above the freezing point at the initiation of each off portion of the cycle, thereby insuring melting of any frozen moisture.

It will be apparent from inspection of Fig 2 that all of the moisture accumulated in duct 36 will be delivered to a sump portion 46 from whence it is passed downwardly through a conduit .49 into a receptacle 50 which is associated with the motor-compressor unit i0, in order that the condensate may be evaporated by the heat of said unit and provide cooling therefor. Special provision is made to prevent entrance of moist air through the conduit 49, as follows.

As will be evident from Fig. 3, a trap 5| is formed in conduit 49 through which the condensed moisture passes. A portion of the moisture will always be present in the trap and this operates to prevent warm humid air from being drawn into the box from the region of the motor-compressor, by virtue of the suction created by the blower. This trap includes double u-shaped portions, one ofV which appears in Fig. 3' at 52, and the other of which terminates in an enlarged spherical junction 53, to prevent any loss of trapped fluid due to a syphoning action. The plane of the U-portion 52 is substantially parallel to the rear surface of the liner, While the legs 54 and 55, which form the second trap portion, lie in a plane at right angles to the plane of the first trap. Before shipment of the refrigerator, this double trap structure can be filled with a liquid which will not freeze during shipping (thereby ensuring presence of a seal-when the refrigerator is rst operated) and it will be understood that the orientation of the two trap portions prevents loss of the sealing liquid, even if the refrigerator is placed on its back during shipment.

While the overall functioning of the apparatus will be clear from the foregoing, a brief summary will be made here, with emphasis on certain features. Existence of undesirably high humidity Within the compartment 4 initiates operation ofthe blower 38, by means of the humidostat 39, thereby causing air to be withdrawn through duct 4|, passed upwardly through duct 36 and thence reinjected into the food compartment. Moisture is given up in the duct 36, as has been described, and the blower operation continues until the relative humidity of the air in the compartment 4 has been reduced to the desired value. This action takes place, under the control of the humidostat or other periodic cycling means employed, without regard to whether or not the motor-compressor is in operation.

If the motor-compressor is functioning during operation of the blower 38, it will be evident that the portion of the suction line (32a) within the passage 36 will be at a cold temperature (the value of which is determined by the specific nature of` the particular design) and the heat transferredv here from the moving air to the suction line will be absorbed by the refrigerating capacity of the main or primary circuit.

On the other hand, if the relative humidity,

within the compartment 4 should become excessive during an ofi portion of the motor-compressor cycle, the line'32a will be at a relatively high defrosting temperature, and its capacity to absorb further heat will be small. Under such conditions, only small amounts of moisture could be condensed in the dehumidifying zone. However, should this reduced heat exchange capacity be insuillcient to restore the desired relative humidity condition within the food compartment,

operation of the compressor will be reestablished automatically, as will now be seen.

As soon as the temperature of the suction line and the adjacent surfaces of the passage 36 rise substantially, heat flows backal'ong said suction line to primary coll 2| and the plate 23. As pointed out above, the control tube 25 is so positioned that it will respond to thisback flow A vof heat, thereby re-establishing operation ofthe compressor I0 and, as will now be understood, reducing the temperature of` suction line portion 32a toward its cold value.

It should, of course, be recognized that evenV under adverse climatic conditions,-the time when the Ablower is l'n operation will not represent a very large proportion of -thetotal operating time` of the refrigerator, and there is always ample time for the defrosting of the heat exchange zone of the present invention. This is evident from the erator having a novel lmoisture-tcondensing arrangement which will not only operate at temperatures well below 32 F., but will also automatically attain a relatively high temperature, periodically. The importance of the resultant prevention of any possibility of frost accumulation in the moisture-condensing zone, will be appreciated.

Moreover, the advantages of the invention are realized by an arrangement which is well adapted for use with present day refrigerators, having a plurality of zones to be maintained at temperature and humidity conditions varying in ,accord` ance with the needs of` different foods.

It willbe evident that, in a broader aspect, the l invention is not limited to the use of a suction conduit in which the temperature varies substantially during the cycle, since the conduit might be operated above freezing at all times, while still providing some of the advantages of the present invention. However, it will be understood that the invention is susceptible of such changes and modifications as may come within the terms of the vappended claims.

I claim:

1. In a refrigerator' having a high humidity storage compartment, Y a cyclically-operable refrigerant circulating system having a portion located exteriorly of said compartment out of contact with the moisture-laden air of said compartment during normal operation of the refrigerator and whose temperature varies during a cycle from a value substantially below the freezing point of water to a value in excess of freez- 2. In a refrigerator, a high humidity storage compartment, an evaporator, compressing means, a suction conduit portion arranged between said evaporator and said compressing means and adapted to operate periodically at a temperature below that prevailing in said storage compartment, said portion being located exteriorly of said compartment and out of contact with the moisture-laden air thereof during normal operation or the refrigerator, and means for passing air from said compartment in heat exchange rela-l tion with said conduit portion to condense moisture from the aix'.

3. In a refrigerator, a high humidity storage compartment, an evaporator, cyclically-operable compressing means, a suction conduitarranged between said evaporator and said compressing means and at least a portion of which is adapted to operate at temperatures which vary during a cycle from a lower value below that prevailing in said storage compartment to a higher value in excess of the freezing point of water, said portion being located exteriorly of said compartment and out of contact with the moisture-laden air thereof during normal operation of the refrigerator, and means for passing air from said compartment in heat exchange relation with said suction conduit portion to condense moisture from the air'.

4. In a refrigerato a high humidity storage compartment, an evaporator, cyclically-operable compressing means, a suction conduit arranged between said evaporator and said compressing means and at least a portion of which is adapted to operate at temperatures which vary during a cycle from subfreezing to superfreezing values, said portion being located exteriorly of said compartment out of contact with the moisture-laden air thereof during normal operation of the refrigerator, and means for passing air from said compartment in heat exchange relation with said suction conduit portion to condense moisture from the air.

5. A construction in accordance with claim l, wherein said last means includes an element responsive to an increase in relative humidity above a predetermined value to initiate action of the said last means and is further adapted to maintain the air movement until the relative humidity is reduced to said predetermined value.

6. In a refrigerator, a high humidity storage compartment, an evaporator, cyclically-operable compressing means, a suction conduit arranged between said evaporator and said compressing means and at least a portion of which is adapted to operate at temperatures which vary during a cycle from a lower value below that prevailing in said storage compartment to a higher value in excess of the freezing point of water, said portion being located exteriorly of said compartment and out of contact with the moisture-laden air thereof during normal operation of the refrigerator, and periodically operable means for passing air from said compartment in heat exchange relation with said suction conduit portion to condense moisture from the air.

'7. A construction in accordance with claim 6, wherein said last means includes an element responsive to an increase in relative humidity above a predetermined value to initiate action of the said last means and is further adapted to maintain the air movement until the relative humidity is reduced to said predetermined value.

8. In a refrigerator, a high humidity storage compartment, an evaporator, compressing means,

evaporator and said compressing means and adapted to operate at least periodically at a temperature below that prevailing in saidstorage compartment, means deilning an air-flow passage in heat exchange relation with said suction conduit portion, and means for passing air from said compartment through said passage and for thereafter returning the air to said compartment.

9. In a refrigerator, an inner liner dening a high humidity storage compartment, a refriga suction conduit portion arranged between said '(5 erant system including a suction conduit portion adapted to operate at least periodically at a temperature below that prevailing in said storage compartment, and air iow passage meansl carried by said inner liner and through which air may be withdrawn from sai-d compartment and returned thereto, a portion of said passage means being arranged in heat exchange relation with said suction conduit portion.

10. In a refrigerator, a high humidity storage compartment, a refrigerant circulating system including a suction conduit portion adapted to operate at least periodically at a temperature below that prevailing in said storage compartment, an vair-flow passage in heat exchange relation with said conduit portion, and means for passing air from said compartment through said passage whereby to reduce the humidity of the air.

1l. In a refrigerator, a high humidity storage compartment, an evaporator, compressing means, a suction conduit arranged between said evaporator and said compressing means and at least a portion of which is adapted to operate at least periodically at temperature below that prevailing in said storage compartment, an air-flow passage in heat exchange relation with said suction conduit portion, means for passing air from said compartment through said passage to condense moisture from the air, and means for controlling the operation of said compressing means, said last means normally being responsive to the temperature condition of said evaporator and further being adapted to initiate operation of said compressor in response to a predetermined temperature condition within said passage.

12. A refrigerator comprising a high humidity compartment, a low-temperature compartment, a cyclically-operable compressor, a secondary refrigerating system for cooling said high humidity compartment, an evaporator for cooling said lowtemperature compartment, an auxiliary evaporator arranged in heat exchange relation with a portion of said secondary system, said evaporators being associated with said compressor to form a series flow refrigerant circuit including a suction conduit portion interconnecting said auxiliary evaporator and said compressor, said suction conduit portion being adapted to operate at temperatures which vary during a cycle from a lower value below that prevailing in said high humidity compartment to a higher value in excess of the freezing point of water, and means for passing air from said high humidity compartment in heat exchange relation with said suction conduit portion to condense moisture from the air.

' 13. In a refrigerator, a high humidity storage compartment, a refrigerant system including a suction conduit portion adapted to operate at least periodically at a temperature below that prevailing in said storage compartment, an air flow passage in heat exchange relation with said suction conduit portion, means for passing air from said compartment through said air ilow passage to condense moisture from the air, and a second passage for conveying condensed moisture out of `said air'ilow passage, said second passage including means preventing ingress of moisture-laden air'fn a reverse direction therethrough.

14. In a refrigerator, avhigh humidity storage compartment, a refrigerant circulating system including a portion so disposed as to be out of contact with the moisture-laden air of said compartment during normal operation of the refrigerator and in which active liquid refrigerant is present intermittently, and means for passing air from said compartment in heat exchange relation with said portion to condense moisture from said air.

15. In a refrigerator, a high humidity storage compartment, a cyclically-operable refrigerant circulating system including a conduit so disposed as to be out of contact with the moistureladen air of said compartment during normal operation of the refrigerator and in which active liquid refrigerant is present during only a portion of a complete cycle, and means for passing air from said compartment in heat exchange relation with said conduit to condense moisture from said air.

. 16. In a refrigerator, a high humidity storage compartment, intermittently-operable compressing means, a conduit portion arranged between said evaporator and said compressing means and in which active liquid refrigerant is present only during operating periods of said compressing means whereby said conduit portion is adapted to function as an evaporator during such operating periods, said portion further being so dis'- posed as to be out of Contact with the moistureladen air of said compartment during normal i area disposed out of contact with the moistureoperation of the refrigerator, and means for periodically eiecting heat exchange between the laden air-of said compartment during normal operation of the refrigerator and in high heat exchange relation with said suction conduit portion,. and means providing for introduction of compartment air into said area to condense moisturefromsaid air.

18. In a refrigerator, a high humidity storage compartment, a refrigerant vcirculating system including a suction conduit portion adapted to operate -at least periodically at a temperature below that prevailing in saidstorage compart- 'ment and disposed out oi' contact with 'the moisture-laden air of the compartment during normal operation of the refrigerator, and means responsive to the humidity condition of the air within said compartment and effective to establish a high heat exchange association of said air with said suction conduit portion in response to an increase in humidity above a predetermined value.

' JOHN J. BAUMAN.

REFERENCES CITED The following references are of record in the file oi this patent:

UNITED STATES PATENTS 

